Bentham held that there are advantages to a moral philosophy based on a principle of utility. To begin with, the principle of utility is clear (compared to other moral principles), allows for objective and disinterested public discussion, and enables decisions to be made where there seem to be conflicts of (prima facie) legitimate interests. Moreover, in calculating the pleasures and pains involved in carrying out a course of action (the “hedonic calculus”), there is a fundamental commitment to human equality. The principle of utility presupposes that “one man is worth just the same as another man” and so there is a guarantee that in calculating the greatest happiness “each person is to count for one and no one for more than one.”

For Bentham, then, there is no inconsistency between the greatest happiness principle and his psychological hedonism and egoism. Thus, he writes that moral philosophy or ethics can be simply described as “the art of directing men’s action to the production of the greatest possible quantity of happiness, on the part of those whose interest is in view.”
  

Source: iep

For an excellent full discussion of Bentham's dictum "everyone to count for one", and it's treatment by Sidgwick and Mill, click here.

for a more advnced article click here.

For a lecture fro Yale on the equality in Benthamite thought click here.